The use of calcium carbonate as an abrasive in toothpaste and in tooth powders is well known in the art. For example, U.S. Pat. No. 3,966,863, to G. C. Forward et al., discloses an oral hygiene composition having anticariogenic activity containing an ionic fluoride, an ionic monofluorophosphate and a calcium carbonate abrasive having a median diameter of less than 40 microns.
U.S. Pat. No. 4,102,992, to W. B. Davis, discloses a dentifrice containing a calcium carbonate cleaning agent in particle size form having a weight median diameter of 10 to 15 microns and, in addition, a polymeric material, such as polymethylmethacrylate, having a particle size of 40 to 100 microns, which polymeric material reduces the abrasivity of the calcium carbonate.
U.S. Pat. No. 4,587,120, to T. Ozawa et al., discloses dentifrice compositions containing calcium hydrogen phosphate anhydride whose crystallite has an average size of about 300 to about 3,500 angstroms, as measured by X-ray diffractometry, which are claimed to have improved cleaning action without an increase in abrasiveness.
U.S. Pat. No. 4,029,760, to Y. De Roeck et al., discloses a dentifrice composition containing carragheenan as a gingivitis-controlling agent, and other usual dentifrice ingredients, including powdered calcium carbonate as the abrasive material.
The prior art discussed above indicates that calcium carbonate or other abrasives have been included in dentifrice preparations, with a specified particle size dependent upon the abrasive material selected and the other ingredients present. However, in practice, calcium carbonate included in dentifrice compositionsas an abrasive generally has a particle size between 1 and 10 microns in order to observe abrasivity limitations recognized in good dental practice.
It is also well known in the art that mineral adjuvants such as calcium carbonate are added to chewing gum compositions to act as fillers or to provide non-stick properties. Thus, for example, U.S. Pat. No. 4,357,355, to E. Koch et al., discloses a non-stick bubble gum base composition that contains about 5% to about 25% by weight of calcium carbonate.
A number of chewing gum compositions have been disclosed in the art which are said to inhibit or reduce plaque in the oral cavity. For example, U.S. Pat. Nos. 4,148,872, 4,150,112, 4,156,715, 4,156,716, 4,157,385, 4,159,315, 4,160,054, 4,160,820, 4,161,517, and 4,170,632, all to A. Wagenknecht et al., disclose chewing gum compositions effective in inhibiting or reducing plaque in the oral cavity. These chewing gum compositions contain a chewing gum base and a surface active agent, and, in some instances, a zinc compound or a plaque inhibiting flavor. In addition, a calcium carbonate abrasive may be included in the aforementioned chewing gum compositions.
U.S. Pat. No. 4,400,372, to J. C. Muhler et al., discloses a chewing gum composition containing a chewing gum base, at least one non-toxic source of an acid and calcined kaolin particles having a median diameter of 2 micrometers of less, wherein substantially all of the kaolin particles are less than 20 micrometers in diameter.
U.S. Pat. No. 3,590,120, to J. C. Muhler, discloses a chewing gum composition containing an insoluble gum base; zirconium silicate particles as a cleaning and polishing agent, wherein at least 20% by weight of said particles are up to about 3 microns in size and between 5% and 40% by weight are about 10 to about 20 microns in size; and a dental plaque removing agent which may be sodium carbonate, sodium bicarbonate, or chloroform.
Although calcium carbonate has been used as a mineral adjuvant or filler in chewing gum compositions, calcium carbonate used for this purpose is generally of a particle size ranging from about 3 microns to about 12 microns. In addition, the particle size of the agents specified in the plaque inhibiting chewing gum compositions cited above range in size from about 2 microns or less to about 20 microns. Thus, it is quite surprising that the chewable tooth cleaning composition of the present invention, containing calcium carbonate having a particle size distribution such that about 44% of the particles, based on the total weight of calcium carbonate, are larger than about 74 microns, is effective in removing plaque from the chewing surfaces of the teeth without abrasive damage to or scratching of the tooth surfaces.